How to find whether hydrocarbons are Alkane, Alkene or Alkyne?

 

Answer:

Rule for Alkane :

  • If the number of Hydrogen atoms is 2 more than twice the number of carbon atoms, it is an alkane.
  • General Formula: C n H 2n+2
  •   The formula of Ethane is C 2 H 6 .
  • Number of Carbon Atoms=2
  • Number of Hydrogen Atoms=2*Carbon atoms+2 = 2*2+2 = 4+2 = 6
  • Since the number of Hydrogen atoms is 2 more than twice the number of carbon atoms, it is an alkane.

Rule for Alkene :

  • If the number of Hydrogen atoms is exactly equal to double the number of carbon atoms, it is an alkene.
  • General Formula: C n H 2
  • The formula of Ethene is C 2 H 4 .
  • Number of Carbon Atoms=2
  • Number of Hydrogen Atoms=2*Carbon Atoms = 2*2 = 4
  • Since number of Hydrogen atoms is double number of carbon atoms, it is an alkene

Rule for Alkyne:

  • If the number of Hydrogen atoms is 2 less than double the number of carbon atoms, it is an alkyne.
  • General Formula: C n H 2n-2
  • The formula of Ethene is C 2 H 2 .
  • Number of Carbon Atoms=2
  • Number of Hydrogen Atoms=2*Carbon Atoms-2 = 2*2-2 = 2
  • Since the number of Hydrogen atoms is 2 less than double the number of carbon.
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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo